Imagine what it must have been like for the first human to witness an aurora. It took a while for our species to migrate from its equatorial birthplace to latitudes where auroras are common, so it was a fairly recent event geologically speaking. Still, that first time seeing the shimmers and ribbons playing across a sky yet to be marred by light pollution must have been terrifying and thrilling, and like other displays of nature’s power, it probably fueled stories of gods and demons. The myths and legends born from ignorance of what an aurora actually represents seem quaint to most of us, but it was as good a model as our ancestors needed to explain the world around them.
Our understanding of auroras needs to be a lot deeper, though, because we now know that they are not only a beautiful atmospheric phenomenon but also a critical component in the colossal electromagnetic system formed by our planet and our star. Understanding how it works is key to everything from long-distance communication to keeping satellites in orbit to long-term weather predictions.
But how exactly does one study an aurora? Something that’s so out of reach and so evanescent seems like it would be hard to study. While it’s not exactly easy science to do, it is possible to directly study auroras, and it involves some interesting technology that actually changes them, somehow making the nocturnal light show even more beautiful.
Regular readers will recognise this as the third part of a series exploring blacksmithing for those who have perhaps always fancied having a go but have never quite known where to start. It’s written from a position of the unusual experience of having grown up around a working forge, my dad may now be retired but he has a blacksmith specialising in architectural ironwork.
So far in this series we’ve looked in detail at the hearth and anvil that you might find in a typical forge, and delivered some pointers as to where you might look to find or even construct your own.Those are the signature pieces of equipment you’ll find in a forge, but with them alone you can still not be a blacksmith.
If I Had A Hammer…
An array of hammers of different weights and types.
Given an anvil, a hearth, and a vat of water to quench hot work in, and you’re almost set for your forge, but not quite. Most of a modern blacksmith’s workshop is the standard metalworking assortment of welders and angle grinders, but there is a set of tools that remain essential for blacksmithing alone. Your hammers are what connect you to the work, and can be as individual as the preferences of the blacksmiths themselves. There is no “right” answer to the question of what hammer you should use, instead you should use the one that works best for you. I instinctively favour a round-faced ball-peen hammer because that’s what my dad mostly used, but for example my Dutch friends use square faced cross-peen hammers. Blacksmiths will often make their own hammers to suit their needs, for example my dad made more than one using the high-quality steel of vehicle half-shafts as a starting point. Hardening them is a specialist skill in its own right, and I remember quite a few experiments before he perfected it.
It may well be stating the obvious, but the weight of the hammer influences how much energy it can impart to the work, and in turn the size of work that can be done. Casting an eye over my dad’s hammers the three workaday weights were 2 pound, 3 pound, and 4 pound (roughly 1 kg, 1.5 kg, and 2 kg), allowing a variety from fine work to heavier hitting of larger pieces. In a recent project, making a mediaeval nail, I selected an unsubtle lump hammer to draw out the larger square stock, and a much smaller one to finish it up, create the fine point, and relatively thin head. These are only a subsection of the hammers at his disposal though, like most blacksmiths he has a variety for all tasks, up to sledgehammers. I have frequently taken my turn either holding a piece with tongs while he used a sledgehammer, or on the sledgehammer myself.
Tongs, for Hot Gripping Moments
A selection of tongs, including some designed for very specific tasks. Our thanks to [Igor Nikolic] for making this picture possible.The constant companion to a blacksmith’s hammer is a pair of tongs. These can be bought from blacksmith’s suppliers, but making a pair can be a task within the reach of most smiths. Two identical sides are made from pieces of stock, with long thin handles, a flat piece to form the hinge, and whatever jaw piece is required. It feels like cheating to form the hole for the hinge on a drill press rather than on the anvil with a punch, but riveting it with a short piece of bar is a straightforward enough process. Blacksmiths will have a huge array of tongs with different jaws for specific jobs, built up over years as jobs demand it. If you cast your mind back to the Finnish smith pictured halfway down the first installment of this series, you’ll find several racks of tongs. A later episode of this series will look at making a set of tongs, though we can’t promise in advance the quality of the finished article.
A final moment for today should be spent on the subject of protective equipment. The hazards of blacksmithing are relatively uncomplicated, but some basic protective clothing is still very much worth having. The most obvious hazard is heat, you will be working in a noisy environment with red hot metal and fire. Though you will generate fewer sparks than you’d expect, I have a blacksmith’s leather apron and a set of fire-resistant overalls. Both of these are readily available from blacksmith’s supply stores, and are well worth the investment. There are also a lot of heavy and sharp items involved, not to mention hot particles on the floor. For that reason I also have a set of steel-toecapped workboots rated for hot particles. They aren’t the most elegant of footwear, but they have saved me from a few nasty moments.
I do not have any face protection specifically for blacksmithing, but depending on the work in hand there may be some sparks created. A polycarbonate face shield rated for hot particles should be available from any safety equipment supplier, and shouldn’t cost too much, and is an essential thing to own if you are doing any grinding or rotary wire brushing. Beyond that, there are also leather gloves designed for handling hot metal. I don’t use them because I prefer the feel of the hammer directly and am happy to use a pair of tongs to hold hot pieces of steel.
We’ve taken you through the basic workshop equipment of a blacksmith over the last few episodes of this series, and you should now have a basic idea of the safety kit you would be well advised to own. From this foundation we’ll next take you into the forge and start looking at a few blacksmithing techniques and simple projects, and along the way we’ll see some of the materials involved, too.
The concept of negative resistance has always fascinated me. Of course, a true negative resistance is not possible, and what is meant is a negative differential resistance (NDR). But of course knowing the correct term doesn’t do anything to demystify the topic. Negative resistance sounds like an unusual effect, but it turns out to be relatively common, showing up in places like neon lamps and a number of semiconductor structures. Now’s as good a time as any to dig in and learn more about this common principle.
NDR means a portion of a device’s I/V curve where the current falls with increasing applied voltage. The best-known semiconductor device exhibiting negative resistance is the tunnel diode, also known as the Esaki diode after one of the Nobel-Prize-winning discoverers of the quantum tunneling effect responsible for its operation. These diodes can perform at tremendous speeds; the fastest oscilloscope designs relied on them for many years. As the transistor and other technologies improved, however, these diodes were sidelined for many applications, and new-production models aren’t widely available — a sad state for would-be NDR hackers. But, all hope is not lost.
Rummaging through some old notebooks, I rediscovered an NDR design I came up with in 2002 using two common NPN transistors and a handful of resistors; many readers will already have the components necessary to experiment with similar circuits. In this article, we’ll have a look at what you can do with junkbox-class parts, and in a future article we’ll explore the topic with some real tunnel diodes.
So, let’s see what you can do with a couple of jellybean transistors!
Recently there’s been some buzz in the news that Pepsi, or more accurately the company’s Russian division, had partnered with a startup by the name of StartRocket to experiment with the idea of putting “billboards” in space. After overwhelmingly negative response to the idea on social media, Pepsi’s official line is that the StartRocket experiment was a one-time partnership, and that the company has no plans to push ahead with a space advertising program “at this time”.
Concept art from StartRocket
Had this been the first time a worldwide conglomerate like Pepsi had turned their eyes up into the black and saw dollar signs, you might think that humanity’s brief flirtation with space-bound advertisements was nothing but a social media stunt. But the truth of the matter is that companies such as Coca-Cola and Pizza Hut have been trying to get their products off terra firma since the 1980’s. This isn’t even Pepsi’s first attempt, despite what their PR department might want you to believe right about now.
So why haven’t we seen advertisers putting their money into space advertising schemes? Well, we have, actually. They just haven’t been terribly effective and the average person likely has no recollection of them. We’re seeing considerable excitement about spaceflight in the new media right now with billionaires like Elon Musk and Jeff Bezos battling to see who can build the most outlandish rockets, but historically, you’d do better getting a 10 second spot during the Super Bowl than plastering your logo on the side of a weather satellite.
In honor of Pepsi’s recent blunder, let’s take a look at some of the standout attempts to conquer advertising’s true true final frontier from the last few decades.
Engineering isn’t just about inventing new things. Sometimes, it is all about doing things better, cheaper and faster. That was what Elsie MacGill did for the “Hurricane” fighter plane in World War II, earning her the nickname of “Queen of the Hurricanes”.
Machining is one of those fascinating fields that bridges the pre-scientific and scientific eras. As such, it has gone from a discipline full of home-spun acquired wisdom and crusty old superstitions to one of rigorously analyzed physics and crusty old superstitions.
The earliest machinists figured out most of what you need to know just by jamming a tool bit into spinning stock and seeing what happens. Change a few things, and see what happens next. There is a kind of informal experimentation taking place here. People are gradually controlling for variables and getting better at the craft as they learn what seems to affect what. However, the difference between fumbling around and actually knowing something is controlling for one’s own biases in a reproducible and falsifiable way. It’s the only way to know for sure what is true, and we call this “science”. It also means being willing to let go of ideas you had because the double-blinded evidence clearly says they are wrong.
That last part is where human nature lets us down the most. We really want to believe things that confirm our preconceived notions about the world, justify our emotions, or make us feel better. The funny thing about science, though, is that it doesn’t care whether you believe in it or not. So go get your kids vaccinated, and up your machining game with scientific precision. Let’s take a look.
The tech world has a love for Messianic figures, usually high-profile CEOs of darling companies whose words are hung upon and combed through for hidden meaning, as though they had arrived from above to our venture-capital-backed prophet on tablets of stone. In the past it has been Steve Jobs or Bill Gates, now it seems to be Elon Musk who has received this treatment. Whether his companies are launching a used car into space, shooting things down tubes in the desert, or synchronised-landing used booster rockets, everybody’s talking about him. He’s a showman whose many pronouncements are always soon eclipsed by bigger ones to keep his public on the edge of their seats, and now we’ve been suckered in too, which puts us on the spot, doesn’t it.
Your Johnny Cab is almost here
The latest pearl of Muskology came in a late April presentation: that by 2020 there would be a million Tesla electric self-driving taxis on the road. It involves a little slight-of-hand in assuming that a fleet of existing Teslas will be software upgraded to be autonomous-capable and that some of them will somehow be abandoned by their current owners and end up as taxis, but it’s still a bold claim by any standard.
Here at Hackaday, we want to believe, but we’re not so sure. It’s time to have a little think about it all. It’s the start of May, so 2020 is about 7 months away. December 2020 is about 18 months away, so let’s give Tesla that timescale. 18 months to put a million self-driving taxis on the road. Can the company do it? Let’s find out.